Pro gambler Phil Ivey made headlines last week for cheating… or was he? While playing a high-stakes game of punto banco at Crockford’s, a British casino, Ivey took away almost $12 million in one lucky run. Crockford’s, however, is alleging that Ivey cheated by observing flaws in the cards that let him predict his deals. As of yet, they have no proof that he broke the rules, but casinos have lots of mechanisms in place to identify cheaters. Here are a few of them that you may not know about.